* storagenode/piecestore: Unexport endpoint method
Make an exported endpoint method to be unexported because it's only used
by the same package and makes easy to change without thinking in
breaking changes.
* uplink/ecclient: Use structured logger
Swap sugared logger by the normal structured logger for having the full
stack traces of the error in the debug message.
* storagenode/piecestore: Send gRPC error codes upload
Refactoring in the storagenode/piecestore to send gRPC status error codes
when some of the methods involved by upload return an error.
The uplink related to uploads has also been modified to retrieve the
gRPC status code when an error is returned by the server.
* rename pkg/linksharing to linksharing
* rename pkg/httpserver to linksharing/httpserver
* rename pkg/eestream to uplink/eestream
* rename pkg/stream to uplink/stream
* rename pkg/metainfo/kvmetainfo to uplink/metainfo/kvmetainfo
* rename pkg/auth/signing to pkg/signing
* rename pkg/storage to uplink/storage
* rename pkg/accounting to satellite/accounting
* rename pkg/audit to satellite/audit
* rename pkg/certdb to satellite/certdb
* rename pkg/discovery to satellite/discovery
* rename pkg/overlay to satellite/overlay
* rename pkg/datarepair to satellite/repair
